MOVEMENT IN A LARGE PREDATORY FISH - CORAL TROUT, PLECTROPOMUS-LEOPARDUS (PISCES, SERRANIDAE), ON HERON-REEF, AUSTRALIA

Movement by the larger more mobile species of coral reef fish plays a significant role in determining patterns in abundance and population s tructure. Fish movement is also relevant to the use and effectiveness of marine reserves in managing fish populations. Coral trout are large piscivorous serranids supporting major fisheries on the Great Barrier Reef (GBR). This study reports on the within-reef movement of the com mon coral trout, Plectropomus leopardus, at Heron Reef, southern GBR, over a twelve month period, investigated by tagging and underwater tra cking. Tracking of coral trout revealed no apparent relationship betwe en the area moved and stage of tide or time of day. However, movement areas were affected by the size of fish: in spring a linear relationsh ip between fish size and area of movement was measured, but in summer the largest (male) fish moved over significantly smaller areas than me dium-sized fish. Movement of males may be related to cleaning behaviou r and spawning. Fifty nine percent (n = 101) of the tagged fish were r esighted over periods of 4-5 months, in ''home sites'' measuring simil ar to 2000 m(2). Coral trout were not restricted to home sites, but mo ved on average 2 km along the reef slope; maximum distances of 7-7.5 k m were measured. Coral trout appear to range as mobile, opportunistic predators, but also maintain home sites for access to shelter and clea ning stations.